"Every Sunday is an opportunity for rest..."
This one seems simple at face value and I see why the correct answer is correct.
Just to be clear why the wrong answer is wrong ("Not all Sundays are relaxing"):
Is it like if you said "Every blue heeler is a dog, but some dogs are not cute."....that doesn't mean that all of the blue heelers aren't cute, it just means that of all dogs, some aren't. All the blue heelers could still be cute.
Is that right? I'm sure this is much simpler than I am making it!